Buick V6 engine

The Buick V6, initially marketed as Fireball at its introduction in 1962, is a large V6 engine used by General Motors. The block is made of cast iron and all use two-valve-per-cylinder iron heads, actuated by pushrods.

In 1967, GM sold the design to Kaiser-Jeep. The muscle car era had taken hold, and GM no longer felt the need to produce a V6, considered in North America an unusual engine configuration at the time. The energy crisis a decade later prompted the company to buy the design back from American Motors (AMC), who had by that point bought Kaiser-Jeep, and the descendants of the early 231 continue to be the most-common GM V6.

Though the pre-3800 RWD V6 uses the BOP bellhousing pattern that it inherited from its aluminum V8 ancestor, an oddity of both the FWD and RWD 3800 V6 is that although it is a 90° V6, it uses the GM 60° V6bell housing. For use in the RWD applications, the bellhousings on both the manual and automatic transmissions are altered slightly.

Fireball V6

The first engine in this family was introduced in 1961 with Buick's 198 cu in (3.2 L) engine, the first V6 in an American car. Because it was derived from Buick's 215 cu in (3.5 L) aluminum V8, it has a 90° bank between cylinders and an odd-fire firing pattern that include the two 'phantom' cylinders from the V8 pattern.

198

Buick Division, concerned about the high manufacturing costs of their innovative aluminum 215 V8, sought to develop a cheaper, cast-iron engine based on the same tooling. They settled on an unusual 90° V6 layout that was essentially the architecture of the '215' less two cylinders. In initial form, it had a bore of 3.625 inches (92.08 mm) and stroke of 3.1875 inches (80.96 mm), for an overall displacement of 198 cu in (3.2 L). It weighed about 35 lb (15.9 kg) more than the aluminum engine, but was far cheaper to produce. Dubbed the Fireball V6, it became the standard engine in the 1962 Buick Special. In their test that year, Road & Track was impressed with Buick's "practical" new V6, saying it "sounds and performs exactly like the aluminum V8 in most respects."

225

The bore was increased to 3.75 in (95.3 mm), and stroke increased to 3.4 in (86.4 mm), increasing displacement to 225 cu in (3.7 L). Since the engine was similar to the popular small-block V8 — now with a cast-iron block and displacement of 300 cubic inches, the engine was made cheaply at the same factory with much of the same tooling. This engine was used in Buick's intermediate-sized Special and Skylark models from 1964 to 1967 and Oldsmobile's mid-sized F-85/Cutlass models for 1964 and 1965. Throughout this period, the 225 cubic-inch V6 featured a one-barrel carburetor and was rated at 155 horsepower-exactly the same rating as the base version of the 215 cubic-inch aluminum V8 used from 1961 to 1963.

The V6 was dropped after the 1967 model year in favor of a conventional 250 cubic-inch inline-6 engine built by the Chevrolet division, and the tooling was sold to Kaiser-Jeep.

Dauntless

In 1965, Kaiser-Jeep began using the Buick 225 in Jeep CJs. It was known as the Dauntless 225 and used a much heavier flywheel than the Buick version to dampen vibrations of the odd fire engine. Buick sold the tooling for this engine to Kaiser in 1967, as the demand for the engine was waning steadily in an era of V8s and muscle cars. When American Motors (AMC) bought Jeep, they replaced the V6 with AMC Straight-6 engines.

231

The 1973 oil crisis prompted GM to look for more economical engines than the V8s of 350, 400 and 454/455 cubic inches that powered most General Motors cars and trucks during that time. At that time, the only "small" engines generally offered by GM were built by the Chevrolet division including the 140 cubic-inch OHC aluminum four-cylinder engine used in the subcompact Chevy Vega and a 250 cubic-inch inline six-cylinder then used in smaller Chevy, Buick, Oldsmobile and Pontiac models, whose design roots dated back to the 1962 Chevy II (Nova).

One quick idea was tried by Buick engineers — taking an old Fireball V6 picked up at a junkyard and installing it into a 1974 Buick Apollo. The solution worked so well that GM wanted AMC to put the engine back into production. However, AMC's cost per unit was deemed as too high. Instead of buying completed engines, GM made an offer to buy back the tooling and manufacturing line from AMC in April, 1974, and began building the engines on August 12[1]. With production back within GM, Buick re-introduced the V6 that fall in certain 1975 models — a move made possible by the fact that foundations for the old V6 machinery were still intact at Buick's engine assembly plant in Flint, Michigan, so it was easy to put the old tooling back in place and begin production at least two years ahead of the normal schedule that would have been required to create new tooling. The bore was enlarged to 3.8 in (96.5 mm), dimensions identical to those of the Buick 350 V8, yielding 231 cu in (3.8 L) displacement. 78,349 231s were installed in Buicks for 1975.[2]

The engine, as it had since its creation, had problems with roughness due to the uneven firing pattern inherent in this engine's design, leading a former American Motors executive to crow "It was rougher than a cob." In 1977, Buick devised an innovative "split-pin crankshaft" redesign of the crankshaft, flywheel, and distributor which greatly alleviated the problem, creating a new even-firing version of the engine. Due to difficulties with the new fuel economy and emissions standards, the engine produced just 110 hp (82 kW).

LD5

In 1978, GM began to market the 231 as the 3.8 liter as metric engine sizes became common in the United States. The RPO Code was LD5, though California-emissions versions were called LC6. Starting in 1979, the engine was used in the front-wheel driveBuick Riviera, though still with a longitudinal mounting. Larger valves and better intake and exhaust boosted the power output for 1979.

A turbocharged version was introduced as the pace car at the 1976 Indianapolis 500, and a production turbo arrived in 1978. The turbo 3.8 received sequential fuel injection and distributorless ignition in 1984. In 1986 an air-to-air Garrett intercooler was added and the RPO Code became LC2. The LC2 engine has a bore of 3.80" and a stroke of 3.40". The respective horsepower ratings for 1986 & 1987 were 235 hp (175 kW) & 245 hp (183 kW). The limited production GNX benefitted from additional factory modifications such as a ceramic turbocharger, more efficient Garrett intercooler, low restriction exhaust system and revised programming which resulted in a 276 hp (206 kW) factory rating although it is widely known that the actual power was closer to 300 hp (222 kW).

The turbocharged 1987 Buick RegalGrand National was called America's quickest automobile, and the model continues to be collected and appreciated today.

3.2

A smaller version of this engine was produced in 1978 and 1979 for the Century and Regal. The bore was reduced to 3.5 in (89 mm), resulting in an engine of 196 cu in (3.2 L) piston displacement. The RPO code was LC9. Initially this engine produced 90 horsepower (67 kW), but in 1979 it received the same improvements in the cylinder heads as did the LD5, and therefore power increased to 105 horsepower (78 kW).

4.1

In response to rising gas prices, a larger 252 cu in (4.1 L) version of the 3.8 L LD5 V6 was produced from 1980 through 1984 by enlarging the bore to 3.965 in (100.71 mm). Output was 125 horsepower (93 kW) and 205 lb·ft (278 N·m). This engine was used in many large rear-wheel drive Buicks, and in some models from each of GM's other divisions, including Cadillac which offered the "big" Buick V6 in several models from 1980 to 1984 as a no-cost option to that division's troublesome V8-6-4 engine used in 1981 and early version of the aluminum-block Cadillac 4.1 L (250 cu in) V8 introduced in 1982. It was also the standard powerplant in the front-drive Riviera and Olds Toronado from 1981 to 1984. Addition: the 4.1 block was also used unsuccessfully at Indianapolis for racing. Its only weakness was the intake valve pushrod seals.

3.8 FWD

In mid-1984, the engine was modified for transverse-mounting in smaller, FWD vehicles, and equipped with multiport fuel injection (MPFI). This was updated to sequential fuel injection (SFI) in 1986, and initially produced in two forms, one with flat lifters (tappets), and the other with a roller camshaft and lifters. The latter was offered in various models through 1988. Power produced by this engine was:

3800 V6

Pre-Series I

LN3 Naturally Aspirated

An LN3 installed in a 1989 Pontiac Bonneville. This engine produced 165 hp (123 kW) and 220 lb·ft (298 N·m) of torque.

The 3.8 L (3800 cc) LN3 was an engine produced by General Motors'Buick Division. Introduced in 1988, the 3800 LN3, would later be loosely considered the Pre-Series I, although the older 3.8 SFI (LG3) was still available that year in some models. Designated initially by VIN code C, the 3800 LN3 was a major redesign, featuring changes such as a balance shaft, on-center bore spacing, use of a 3x/18x crank-trigger system, and other improvements. This generation continued in use in several GM products into the 1990s. It produced 165 hp (123 kW) and 220 lb·ft (298 N·m). The LN3 is very closely related to the Series I L27 and Series I L67 Supercharged. In fact, supercharger-related hardware can be fitted to an LN3 without changing the cylinder heads (ECM reprogramming required). The L27 has a two piece, upper plenum intake and lower intake, the LN3 is all one piece.

3300

A smaller 3.3 L 3300 was introduced in 1989 and produced through 1993. It is effectively a lower-deck version of the 3800, with a smaller 3.7 in (93.98 mm) bore and 3.16 in (80.26 mm) stroke for 3344 cc (204 cu in). Like the 3800, it used a cast iron block and heads, push rods, and hydraulic lifters. Unlike the 3800, however, it used a batch-fire injection system rather than sequential injection, as evidenced by the lack of a cam position sensor. Power output was 160 hp (120 kW) at 5200 rpm and 185 lb·ft (251 N·m) at 2000 rpm with a 5500 rpm redline.

Series I

L27 Naturally Aspirated

A 3800 Series I L27 Naturally Aspirated engine installed transversely in a 1995 Buick Regal.

The LN3 was replaced by the 3.8 L (3791 cc, 231 cu in)[3]L27 in 1991-1992 and produced 170 horsepower (130 kW) from 1992 onward, this engine was referred to as the Series I 3800. In Australia, the LN3 was also replaced by the L27 by Holden who used the engine in their series 2 (1991) VN Commodore range. However, the Australian L27 retained the LN3's one piece upper intake and lower plenum. Power was still boosted to 127 kW (170 hp) for the Holden L27. The L36 made its debut in 1995.

A supercharged 3800 (transverse mount) installed in a Buick Riviera for 1995, the last year of Series I L67 production. Power is 225 hp (168 kW)/260 lb·ft (353 N·m) for this version.

L67 Supercharged

The Series I Supercharged engine went through many internal changes and the horsepower changed rapidly between the time it was introduced and the time that the Series II L67 was introduced. The M62 supercharger was manufactured by Eaton, exclusively for the GM 3800 engine. HP was rated at 205 for 1991-1993 engines (models vary), and 225 for 1994-1995 engines. The additional horsepower was gained by using a larger throttle body, roller rockers and epoxy coated supercharger rotors, improving efficiency. The 1994-1995 utilized a 2.85-inch (72.4 mm) pulley versus the 2.55-inch (64.8 mm) pulley used on the 91-93 supercharger.

Series II

Introduced in 1995, the Series II is quite a different engine. Although the stroke for the 3.8 L engine remained at 3.4 in (86 mm), and the bore remained at 3.8 in (97 mm), the engine architecture was vastly changed. The deck height is shorter than the Series I, reducing weight and total engine package size. This required that the piston connecting rods be shortened 1 in (25 mm), and the crankshaft was also redesigned. A new intake manifold improved breathing while a redesigned cylinder head featured larger valves and a higher compression ratio. The result was 205 hp (153 kW) and 230 lb·ft (312 N·m), better fuel economy, and 26 lb (12 kg) lighter overall weight (to 392 lb (178 kg)). The 3800 weighs only 22 lb (10.0 kg) more than the High Feature V6, despite being an all cast iron design.

Although the new intake manifold greatly improved breathing, it was made from plastic. To meet emissions standards, an EGR tube was placed in the
intake manifold to reduce combustion temperatures. Over time the plastic intake manifold cracks, resulting in expensive repairs. The failure can show up as low intake vacuum via leaks, occasional misfiring when running, or most often, unexplained coolant loss. GM is well aware of the issue and even has a TSB (Technical Service Bulletin) 04-06-01-017 which explains the repairs needed that will temporarily resolve the issue. Average mileage when the manifold fails is around 77,000 miles (124,000 km). This TSB affects most 3800 (3.8 L) engines from 1995 to present.

L67 Supercharged

The L67 is the supercharged version of the Series II L36 and appeared in 1996, one year after the normally-aspirated version. It uses the Eaton Generation III M90 supercharger with a 3.8" pulley, a different throttle body, fuel injectors, cylinder heads, and lower intake manifold than the L36 uses. Both engines share the same engine blocks, but compression is reduced from 9.4:1 in the L36 to 8.5:1 for the L67. Power is up to 240 hp (180 kW) and 280 lb·ft (380 N·m) of torque. Final drive ratios are reduced in most applications, for better fuel economy and more use of the engine's torque in the low range. The engine was built in Flint, Michigan. The engine was certified LEV in 2001.

Series III

The Series III motors include many changes. The upper intake manifold is now aluminum on the naturally aspirated models. Intake ports are mildy improved, 1.83" intake valves (instead of 1.80" as on Series II) and 1.52" exhaust valves were introduced in 2003 engines, just before switching to Series III. Electronic throttle control is added to all versions, as is returnless fuel injection. Stronger powdered metal sinter forged connecting rods are used in 2004+ supercharged, and 2005+ naturally aspirated engines, instead of the cast iron style from Series II engines. Emissions are also reduced. In 2005, it was the first gasoline engine in the industry to attain SULEV (Super Ultra Low Emissions Vehicle).

Also note that Series III engines are the base for any 3800 produced for the 2004 year and up. This means the same block, heads, & connecting rods apply to any remaining Series II engines made after 2004 also. The difference is that Series III engines received the new superchargers (Generation 5 - Eaton m90 - if equipped), intake manifolds, fuel systems, and electronics.

L26 Naturally Aspirated

The L26 is the Series III version of the 3800. It is still a 3.8 L (231 cu in) design. Compression remains at 9.4:1 as with previous L36's, but the aluminum upper intake (2004+) and stronger connecting rods (2005+) are the primary physical changes. The powdered metal connecting rods were meant to be introduced in 2004 along with the L32's, but the GM plant in Bay City, Michigan that supplies the Flint, Michigan plant could not achieve the desired production dates in time for that engine year.

L32 Supercharged

The L32 is a superchargedSeries III.
Introduced in 2004, the main differences between the L67 and the L32 is the L32's electronic throttle control, slightly improved cylinder head design, and updated Eaton supercharger, the Generation 5 M90. Power output is up to 260 HP (194 kW) in the Grand Prix GTP.

Future of the 3800

Production of the renowned 3800 V6 engine was officially ended on Friday, August 22, 2008 when plant 36 was closed. There was a closing ceremony and speakers who extolled the virtues of the engine, but none that could give a definitive answer why they did away with it. Originally GM had set this date for January 1, 1999 Template:Correction needed, however due to the vast number of complaints from both investors and customers because of the popularity and reliability of the engine, the date was extended. At the end of production, the LZ4 3500 OHV V6 will replace the naturally aspirated 3800 applications, and the LY7 3600 DOHC V6 will replace the supercharged 3800 applications.